Not All Nanotubes are Similar

Carbon has been proving itself to be a very interesting element, thanks to the fantastic properties it can have, just by changing its structure. As molecular structure dictates many properties of a material, it is believed that other materials with near-identical structures, if different components, would have similar properties. Researchers at MIT though have recently tested one of these similar materials and found that its properties are not only different from the carbon version, but practically opposite.

Carbon nanotubes are cylinders made of carbon just nanometers wide, making them a thousand times smaller than a human hair. Amongst other properties, they are well-known for superlubricity, which is an extreme form of frictionlessness. To measure this property, the MIT researchers built a device that can pull on the ends of nested nanotubes, so as the force grows, the nanotubes will slide along each other to stretch. Along with the nest carbon nanotubes (CNTs), the researchers also tested nested boron nitride nanotubes (BNNTs). They found that the BNNTs suffer significantly more friction than CNTs, which was very surprising. Especially as bulk BNNTs are actually used as a lubricant.

Exactly why there is such a difference between the two kinds of nanotubes is unknown, but it could be related to their electrical properties, as CNTs can be conducting or semiconducting, while BNNTs are insulating. This discovery could have many interesting implications and applications, such as shock absorbers and new nanoelectromechanical devices.